A motor vehicle is equipped with headlights intended to produce a light beam which lights the road in front of the vehicle, particularly at night or in cases of reduced brightness.
These headlights can generally be used according to two lighting modes: a first, “high beam” mode and a second, “low beam” mode.
The “high beam” mode makes it possible to produce a long range light beam, which strongly lights the road far in front of the vehicle.
The “low beam” mode provides a lighting of the road that is of more limited range, but that nevertheless offers a good visibility. The more limited range makes it possible not to dazzle the other users of the road.
These two lighting modes are complementary. The driver of the vehicle must manually change mode according to the circumstances, at the risk of inadvertently dazzling another road user. In practice, the act of manually changing lighting mode can lack reliability and sometimes prove hazardous.
Furthermore, the low beam mode provides a visibility that is sometimes unsatisfactory for the driver of the vehicle.
To improve the situation, headlights provided with an ADB (Adaptive Driving Beam) adaptive lighting function have been proposed. Such an ADB function is intended to automatically detect a user of the road likely to be dazzled by a lighting beam emitted in high beam mode by a headlight, and to modify the outline of this lighting beam so as to create a shadow zone at the point where the detected user is located.
The advantages of the ADB function are manifold: ease of use, better visibility compared to lighting in low beam mode, better reliability for the change of mode, risk of dazzling greatly reduced, safer driving.
One known lighting system for a motor vehicle headlight provided with an ADB function comprises a primary optical module. The primary optical module comprises a plurality of light sources, for example light-emitting diodes, associated with three respective light guides. A secondary projection optical element, for example a lens, is associated with the primary optical module.
The light emitted by each light-emitting diode penetrates into the associated light guide and is emitted by an output end of the guide, of rectangular form. The associated secondary optical element projects an image of the output face of each light guide to form, in front of the vehicle, vertical light segments. The light segments produced are partially superposed in the transverse direction. The light-emitting diodes can be switched on independently of one another, selectively, to obtain the desired lighting.
Such a lighting system does however present certain drawbacks.
One such primary optical module, comprising a plurality of independent light guides each associated with a light source is very complex and costly to produce.
Furthermore, the choice of material for producing the optical elements of such a lighting system is particularly limited. Thus, it is not possible to use glass. The optical elements can be produced by injection moulding of polycarbonate, but the injection conditions must be observed precisely, which leads to production difficulties.
Furthermore, the segmented light beam comprises a single row of segments which extend over all the height of the segmented light beam. Because of this, when one segment is off, the road is dark over a more vertically extended zone than is necessary to avoid dazzling a user of the road.
Moreover, for visual comfort reasons and for regulatory reasons, it is preferable for two adjacent segments to be contiguous for the global light beam to light the road uniformly.
Now, the known solutions do not make it possible to obtain contiguous light segments simply, particularly when the light sources are too spaced apart from one another. To obtain a uniform lighting, it is for example necessary to employ complex primary optics.